APPLICATION OF ZONAL LES/ILES APPROACHES TO AN UNSTEADY COMPLEX GEOMETRY FLOW

摘要

Flow and heat transfer inside an idealized electronics system is simulated using Large-eddy Simulation (LES) related approaches. These include: Yoshizawa LES (Large Eddy Simulation), DES (Detached Eddy Simulation), LNS (Limited Numerical Scales) and other hybrid LES-RANS (Reynolds Averaged Navier-Stokes) approaches including a new ILES (Implicit LES)-RANS method. Modelling this unsteady complex geometry flow is found challenging. Performances of the LES related methods are compared with zonal EASM (Explicit Algebraic Stress Model) unsteady RANS (URANS) results and measurements. For mean velocities, the (I)LES-RANS methods have similar accuracies to the zonal EASM and LES. Velocity results are in a reasonable agreement with measurements. However, as far as heat transfer is concerned, none of the models investigated performs well. Significant heat transfer discrepancies exist. The LNS performs poorly for both the flow field and heat transfer and DES proves impossible to converge. This is partly attributed to the irregular interface arising from the DES interface being grid controlled.